Insert molded article, insert molding method, and insert molding apparatus

ABSTRACT

An insert molding apparatus includes a forming die in which a first part is arranged, and that molds resin such that a portion of the first part is exposed; and a first mounting part that is arranged at a portion where the first part is exposed, and that has a passage that passes through a space in the forming die into which the molten resin is supplied and a portion where the first part is arranged.

INCORPORATION BY REFERENCE

This is a divisional of U.S. application Ser. No. 14/090,291 filed Nov.23, 2013 (allowed), which claims priority to Japanese Patent ApplicationNo. 2012-262918 filed on Nov. 30, 2012. The entire disclosure of theprior application is considered part of the disclosure of theaccompanying divisional application, and hereby incorporated byreference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The invention relates to an insert molded article in which a pluralityof types of parts are used for specific insert parts, an insert moldingmethod for manufacturing this insert molded article, and an insertmolding apparatus used in this insert molding method.

2. Description of Related Art

Insert molding is known as a method for integrating a part with resin.In insert molding, a part is integrated with set resin by injectingmolten resin around the part while the part is arranged inside of aforming die. For example, Japanese Patent Application Publication No.2005-297387 (JP 2005-297387 A) describes a case for an electroniccontrol unit as an insert molded article.

Also, Japanese Patent Application Publication No. 2012-28029 (JP2012-28029 A) describes technology for preventing wrong assembly in alever-type connector. With the lever-type connector described in JP2012-28029 A, a wrong-assembly preventing protrusion that prevents wrongassembly of a wire cover is provided on the wire cover. Thewrong-assembly preventing protrusion abuts against an arm of a leverwhen the wire cover is assembled in the opposite direction from theassembly direction of the lever. Wrong assembly of the wire cover isable to be detected by the wrong-assembly preventing protrusion abuttingagainst the arm of the lever.

There are cases in which a plurality of types of parts are used forspecific insert parts in an insert molded article. In such cases, whenthe specific insert parts are assembled in a forming die, it is possiblethat, of the specific insert parts, one type of insert part may bewrongly assembled in a location where a different type of insert part issupposed to be assembled. However, with conventional insert moldingtechnology, no thought has been given to how to detect wrong assemblywhen the type of insert part is wrong. Therefore, it is difficult todetermine whether a wrong part has been assembled or a correct part hasbeen assembled, when there is only a small difference in appearancebetween different types of insert parts, for example.

SUMMARY OF THE INVENTION

The invention thus provides an insert molded article, an insert moldingmethod, and an insert molding apparatus, in which wrong assembly of aninsert part is able to be easily detected.

A first aspect of the invention relates to an insert molded article thatincludes a first part; and a resin case having a protruding portion thatis formed exposing a portion of the first part, and is adjacent to aportion where the first part is exposed, and protrudes from a surface ofthe resin case.

A second aspect of the invention relates to a method for forming aninsert molded article that includes a first part, and a resin casehaving a protruding portion that is formed exposing a portion of thefirst part, and is adjacent to a portion where the first part isexposed, and protrudes from a surface of the resin case. This methodincludes arranging the first part in a forming die; arranging a mountingpart that has a passage that passes through a cross-section thereof, soas to cover a portion where the first part is exposed from the resincase and such that the passage is blocked off by the first part; andforming the resin case by pouring molten resin into the forming die.

A third aspect of the invention relates to an insert molding apparatusthat includes a forming die in which a first part is arranged, and thatmolds resin such that a portion of the first part is exposed; and afirst mounting part that is arranged at a portion where the first partis exposed, and that has a passage that passes through a space in theforming die into which the molten resin is supplied and a portion wherethe first part is arranged.

According to these aspects it is possible to easily determine whether awrong insert part has been assembled or a correct insert part has beenassembled.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, advantages, and technical and industrial significance ofexemplary embodiments of the invention will be described below withreference to the accompanying drawings, in which like numerals denotelike elements, and wherein:

FIG. 1 is a perspective view of an insert molded article according toone example embodiment of the invention;

FIG. 2 is a side view and a sectional view of insert nuts;

FIG. 3 is a block diagram schematically showing an insert moldingapparatus;

FIG. 4 is a perspective view of a first mounting member;

FIG. 5 is a side view of a state in which the first mounting member isattached to a second type of nut arranged on a first placement portionin the insert molding apparatus;

FIG. 6 is a perspective view of a corner portion of an insert moldedarticle when an insert nut is not wrongly assembled; and

FIG. 7 is a perspective view of a corner portion of the insert moldedarticle when the insert nut is wrongly assembled.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, example embodiments of the invention will be described indetail with reference to FIGS. 1 to 7.

[Insert Molded Article]

FIG. 1 is a perspective view of an insert molded article 10 according toone example embodiment of the invention. The insert molded article 10 inthis example embodiment is a case for an electronic control unit (ECU).The insert molded article 10 is a case that is generallyrectangular-shaped when viewed from above and is open on top, as shownin FIG. 1. Insert nuts 11 and 12 are embedded, as specific insert parts(specific parts) for which a plurality of types of parts are used, inthe insert molded article 10. The insert nuts 11 and 12 are embedded ineach of four corners of the insert molded article 10. The electroniccontrol unit is such that a lid member, not shown, that covers theopening of the insert molded article 10 is fixed by bolts that fasten tothe insert nuts 11 and 12. Transparent insert parts in the area insidethe broken line in FIG. 1 are indicated by broken lines. Insert partsother than the insert nuts 11 and 12 and a bus bar 15 that will bedescribed later are omitted in FIG. 1.

FIG. 2 is a side view and a sectional view of the insert nuts 11 and 12.A first type of nut 11 and a second type of nut 12 are used for the fourinsert nuts 11 and 12 of the insert molded article 10. In FIG. 2, theinsert nuts 11 and 12 are shown in a side view on the left side of thedashed line and in a sectional view on the right side of the dashedline. As shown in FIG. 1, in the insert molded article 10, there arethree of the first type of nut 11, and one of the second type of nut 12.The first type of nut 11 and the second type of nut 12 are both formedin a generally cylindrical shape. The shape and dimensions of an endportion of the first type of nut 11 are different from the shape anddimensions of an end portion of the second type of nut 12.

Each of the first type of nuts 11 is embedded in the insert moldedarticle 10 such that a portion of the first type of nut 11 is exposed.With the insert molded article 10, a recessed portion 130 and aprotruding portion 131 that will be described later are formed aroundeach of the first type of nut 11 (see FIG. 6). An upper end surface ofthe second type of nut 12 is overlapped by a metal bus bar 15, so thesecond type of nut 12 differs from the first type of nut 11 in that theupper end surface is not exposed. One end of the bus bar 15 has athrough-hole through which a bolt can be inserted. The other end of thebus bar 15 is connected to a heat sink, not shown, provided on theinsert molded article 10.

A portion of the first type of nut 11 except for a first end portion 11b and a second end portion 11 c is a knurled portion 11 a that has beenknurled. An outer diameter of the knurled portion 11 a is uniform in anaxial direction. Also, with the first type of nut 11, the first endportion 11 b and the second end portion 11 c are the same shape andsize. Each end portion 11 b and 11 c has a smooth cylindrical surface asa result of being cut (i.e., machined). An outer diameter of each endportion 11 b and 11 c is uniform in the axial direction, and is justslightly smaller than the outer diameter of the knurled portion 11 a.

A portion of the second type of nut 12 except for a first end portion 12b is a knurled portion 12 a that has been knurled. A second end portion12 c is part of the knurled portion 12 a. An outer diameter of theknurled portion 12 a is uniform in the axial direction. Also, the firstend portion 12 b has a smooth cylindrical surface as a result of beingcut (i.e., machined). An outer diameter of the first end portion 12 b isuniform in the axial direction, and is just slightly smaller than theouter diameter of the knurled portion 12 a.

Continuing on, the first type of nut 11 and the second type of nut 12will be compared. A height of the first type of nut 11 is higher than aheight of the second type of nut 12 by an amount corresponding to thethickness of the bus bar 15. Also, the outer diameter of the knurledportion 11 a of the first type of nut 11 is the same as the outerdiameter of the knurled portion 12 a of the second type of nut 12. Theouter diameter of the knurled portions 11 a and 12 a is 9 mm, forexample. Also, the outer diameter of the end portions 11 b and 11 c ofthe first type of nut 11 is the same as the outer diameter of the firstend portion 12 b (i.e., the cut end portion) of the second type of nut12. The outer diameter of these cut end portions 11 b, 11 c, and 12 b is8.5 mm, for example. The outer diameter of the second end portion 12 cof the second type of nut 12 is just slightly larger than the outerdiameter of the cut end portions 11 b, 11 c, and 12 b.

<Insert Molding Apparatus>

Continuing on, an insert molding apparatus 100 used to manufacture theinsert molded article 10 will now be described.

FIG. 3 is a block diagram schematically showing the insert moldingapparatus 100. The insert molding apparatus 100 includes a forming die101 that has an upper die 102 and a lower die 103, an opening/closingmechanism, not shown, for opening and closing the forming die 101, aresin injecting device 104 for injecting molten resin inside the formingdie 101, and a plurality of mounting members 111 and 112 (a so-calledpiece for insert molding), as shown in FIG. 3. A fill port 110 intowhich a nozzle of the resin injecting device 104 is inserted is formedin the forming die 101.

A first placement portion 121 for arranging the first type of nut 11 anda second placement portion 122 for arranging the second type of nut 12are formed on a bottom surface of the lower die 103. The first placementportion 121 is provided in three locations, of the corner portions infour locations on the bottom surface of the lower die 103. The secondplacement portion 122 is provided in the remaining one location. Thefirst placement portion 121 and the second placement portion 122 are allthe same size and shape. The placement portions 121 and 122 are circularrecessed portions. The end portions 11 b and 11 c of the first type ofnut 11, as well as the first end portion 12 b of the second type of nut12, are able to fit into the placement portions 121 and 122.

The plurality of mounting members 111 and 112 are formed by a firstmounting member 111 for the first type of nut 11, and a second mountingmember 112 for the second type of nut 12. In the insert moldingapparatus 100, there are three of the first mounting members 111, andone of the second mounting member 112.

FIG. 4 is a perspective view of one of the first mounting members 111.Hereinafter, the first mounting members 111 and other portions may bereferred to in the singular to simplify the description. FIG. 4 showsthe first mounting member 111 upside down from the state in which it isshown in FIG. 3. FIG. 5 is a side view of a state in which the firstmounting member 111 is attached to the second type of nut 12 arranged onthe first placement portion 121 in the insert molding apparatus 100. Thefirst mounting member 111 is mounted onto the first type of nut 11 thatis assembled to the first placement portion 121, before molten resin isinjected into the forming die 101. The first mounting member 111 holdsdown the first type of nut 11 using restoring force of an elastic member108 (e.g., an elastic spring) attached to the first mounting member 111.

The first mounting member 111 includes a disk-shaped main body portion111 a that is pressed against the end surface of the first type of nut11, and a cylindrical peripheral wall portion 111 b that rises from themain body portion 111 a, as shown in FIG. 4. The main body portion 111 aand the peripheral wall portion 111 b are integrated together. An innerdiameter of the peripheral wall portion 111 b is set so as able to fitthe end portions 11 b and 11 c of the first type of nut 11, but not ableto fit the second end portion 12 c (i.e., the end portion that is partof the knurled portion 12 a) of the second type of nut 12. Morespecifically, the inner diameter of the peripheral wall portion 111 b islarger than the outer diameter of the end portions 11 b and 11 c of thefirst type of nut 11, and smaller than the outer diameter of the secondend portion 12 c of the second type of nut 12. When the main bodyportion 111 a is pressed against the end surfaced of the first type ofnut 11 by the elastic member 108, the peripheral wall portion 111 b ispositioned on the outside of the outer peripheral surface of the endportion 11 c of the first type of nut 11.

Notches 111 c are formed from a tip end side in the peripheral wallportion 111 b. The depth of the notches 111 c is lower than the heightof the peripheral wall portion 111 b. In this example embodiment, thereare two notches 111 c, but there may also be only one notch 111 c orthree or more notches 111 c. Also, the depth of the notches 111 c may beequal to the height of the peripheral wall portion 111 b.

The second mounting member 112 is formed in a disk-shape. An outerdiameter of the second mounting member 112 is larger than an outerdiameter of the second end portion 12 c of the second type of nut 12.The second mounting member 112 is mounted onto the second type of nut 12that is assembled to the second placement portion 122, before moltenresin is injected into the forming die 101. The second mounting member112 holds down the second type of nut 12 via the bus bar 15, usingrestoring force of an elastic member 109 (e.g., an elastic spring)attached to the second mounting member 112.

According to the structure described above, when the first type of nut11 is attached to the first placement portion 121, an inside surface ofthe main body portion 111 a of the first mounting member 111 contactsthe end surface of the first type of nut 11, as shown in FIG. 3. On theother hand, when the second type of nut 12 is attached to the firstplacement portion 121, a tip end surface of the peripheral wall portion111 b of the first mounting member 111 contacts the end surface of thesecond type of nut 12, as shown in FIG. 5. As a result, a gap fordetecting wrong assembly (hereinafter, simply referred to as a“wrong-assembly detection gap”) 135 is formed between the inside surfaceof the main body portion 111 a of the first mounting member 111 and theend surface of the second type of nut 12. This wrong-assembly detectiongap 135 is connected via the notches 111 c to a space inside the formingdie 101 that is injected with molten resin. In the insert moldingapparatus 100, the wrong-assembly detection gap 135 that is connectedvia the notches 111 c to the space inside the forming die 101 that isinjected with molten resin is formed to the inside of the peripheralwall portion 111 b only when the second type of nut 12, from among thefirst type of nut 11 and the second type of nut 12, is assembled to thefirst placement portion 121.

<Insert Molding Method>

Continuing on, an insert molding method using the insert moldingapparatus 100 will be described. Hereinafter, a case in which the insertnuts 11 and 12 are correctly assembled will be described.

With this insert molding method, an placement process is performed inwhich the insert nuts 11 and 12 are arranged on the first placementportion 121 provided in three locations and the second placement portion122 provided in one location on the bottom surface of the lower die 103of the forming die 101. The first end portion 11 b (or the second endportion 11 c) of each of the first type of nuts 11 is fitted into thecorresponding first placement portion 121. The first end portion 12 b ofthe second type of nut 12 is fitted into the second placement portion122. In this placement process, insert parts other than the insert nuts11 and 12 are also assembled. The bus bar 15 is assembled in apredetermined position of the forming die 101 such that one end of thebus bar 15 overlaps with the upper surface of the second type of nut 12.

Continuing on, a die-closing process in which the upper die 102 ismounted onto the lower die 103 is performed. In this die-closingprocess, the first mounting member 111 is mounted onto the first type ofnut 11, and the second mounting member 112 is mounted onto the secondtype of nut 12. In the closed forming die 101, the first mounting member111 holds down the second end portion 11 c (or the first end portion 11b) of the first type of nut 11, and the second mounting member 112 holdsdown the second end portion 12 c of the second type of nut 12.

Next, an injection process in which a nozzle of the resin injectingdevice 104 is inserted into the fill port 110 and molten resin isinjected into the forming die 101 from the resin injecting device 104 isperformed. During this injection process, the position of the first typeof nut 11 is maintained by the first mounting member 111, and theposition of the second type of nut 12 is maintained by the secondmounting member 112. Also, molten resin flows into the notches 111 c ofthe peripheral wall portion 111 b of the first mounting member 111.

After the injection process, a setting process in which the molten resinin the forming die 101 is set (i.e., solidified) is performed. Thenafter the resin in the forming die 101 has set, a die-opening process inwhich the forming die 101 is opened so that the upper die 102 separatesfrom the lower die 103 is performed. In this die-opening process, thefirst mounting member 111 is removed from the first type of nut 11, andthe first type of nut 11 is released from the state in which it is helddown by the first mounting member 111. Also, the second type of nut 12is also released from the state in which it is held down by the secondmounting member 112. The insert molded article 10 shown in FIG. 1 iscompleted by performing the processes described above and the like.

FIG. 6 is a perspective view of a corner portion of the insert moldedarticle 10 when the insert nuts 11 and 12 are not wrongly assembled(i.e., when the insert nuts 11 and 12 are assembled correctly). In theinsert molded article 10, a portion of the second end portion 11 c (orthe first end portion 11 b) of the first type of nut 11 is an exposedportion that is exposed on the outside. As shown in FIG. 6, the recessedportion 130 is formed as an impression of the peripheral wall portion111 b of the first mounting member 111 that is mounted to the first typeof nut 11 when insert molding is performed. Furthermore, two of theprotruding portions 131 that protrude from the bottom surface of therecessed portion 130 are formed as impressions of the two notches 111 cformed in the peripheral wall portion 111 b. The recessed portion 130 isa generally circular groove. The protruding portions 131 are protrusionsthat are generally rectangular when viewed from above.

Here, the diameter of the inside of the recessed portion 130 is equal tothe inner diameter of the peripheral wall portion 111 b of the firstmounting member 111. Therefore, the inner diameter of the peripheralwall portion 111 b can be known based on the shape and dimensions of therecessed portion 130, even without looking at the insert moldingapparatus 100. On the other hand, the diameter of the inside of therecessed portion 130 is smaller than the outer diameter of the secondend portion 12 c of the second type of nut 12 that is embedded in theinsert molded article 10. The shape and dimensions of the recessedportion 130 indicate that if the second type of nut 12 were to bearranged on the first placement portion 121, the tip end surface of theperipheral wall portion 111 b would contact the end surface of thesecond end portion 12 c of the second type of nut 12 without the secondend portion 12 c of the second type of nut 12 fitting together with theperipheral wall portion 111 b, such that the wrong-assembly detectiongap 135 would be formed to the inside of the peripheral wall portion 111b. Also, the shape and dimensions of the protruding portion 131correspond to the notches 111 c in the peripheral wall portion 111 b.Therefore, the shape and dimensions of the notches 111 c in theperipheral wall portion 111 b are able to be known even without lookingat the insert molding apparatus 100. The shape and dimensions of therecessed portion 130 indicate that the wrong-assembly detection gap 135is connected via the notches 111 c to the space into which the moltenresin is injected.

<Method for Detecting Wrong Assembly of an Insert Nut>

Continuing on, a method for detecting wrong assembly when the insertnuts 11 and 12 are wrongly assembled in the placement process of theinsert molding method will be described. FIG. 7 is a perspective view ofa corner portion of the insert molded article 10 when the insert nuts 11and 12 are wrongly assembled. Hereinafter, a case will be described inwhich the second type of nut 12 is mistakenly assembled to the firstplacement portion 121 to which the first type of nut 11 should beassembled.

In this case, in the placement process, the first end portion 12 b ofthe second type of nut 12 is fitted into the first placement portion121. In this state, even if a worker looks at the second type of nut 12that is wrongly assembled, the height and outer diameter of the endportion of the second type of nut 12 are only slightly different thanthey are with the first type of nut 11, so the worker may not notice thewrong assembly. Then the first mounting member 111 will be mounted tothe second end portion 12 c of the second type of nut 12.

However, as described above, the inner diameter of the peripheral wallportion 111 b of the first mounting member 111 is set such that thesecond end portion 12 c of the second type of nut 12 is unable to fit.Therefore, in the injection process, the tip end surface of theperipheral wall portion 111 b of the first mounting member 111 contactsthe end surface of the second end portion 12 c of the second type of nut12, and the first mounting member 111 rides on the second type of nut12, as shown in FIG. 5. The wrong-assembly detection gap 135 is formedbetween the main body portion 111 a of the first mounting member 111 andthe end surface of the second end portion 12 c of the second type of nut12. The wrong-assembly detection gap 135 is connected via the notches111 c to the space inside the forming die 101 into which molten resin isinjected. Therefore, molten resin that has been injected into theforming die 101 when the injection process is performed flows inside thesecond type of nut 12 and the wrong-assembly detection gap 135 throughthe notches 111 c. The wrong-assembly detection gap 135 is filled withmolten resin. As a result, in the insert molded article 10 after thedie-opening process, the end surface of the second end portion 12 c ofthe second type of nut 12 is covered by resin 136, as shown in FIG. 7.Also, the recessed portion 130 that forms when the first type of nut 11is assembled to the first placement portion 121 will not form around thesecond type of nut 12. When the end surface of the second end portion 12c of the second type of nut 12 is covered by the resin 136, a worker iseasily able to visually notice it. Also, whether the end surface of thesecond end portion 12 c of the second type of nut 12 is covered is alsoable to be easily determined using an imaging device such as a camera.Therefore, wrong assembly of the insert nuts 11 and 12 is able to beeasily detected.

When the first type of nut 11 is wrongly assembled to the secondplacement portion 122, the first type of nut 11 is higher than thesecond type of nut 12, so the bus bar 15 will bend when it (i.e., thebus bar 15) is mounted to the upper side of the first type of nut 11.Therefore, wrong assembly can be detected relatively easily when theplacement process is performed.

Other Example Embodiments

The example embodiment described above may also be structured asfollows.

In the example embodiment described above, both the shape and size ofdifferent types of specific insert parts (i.e., insert nuts) aredifferent. However, it is sufficient that at least one of the shape andthe size be different among different types of specific insert parts.

Also, in this example embodiment, the peripheral wall portion 111 b isformed along the entire periphery of the first mounting member 111, butthe peripheral wall portion 111 b may also be formed on only a portionof the first mounting member 111 as long as the wrong-assembly detectiongap 135 is formed by the tip end surface of the peripheral wall portion111 b abutting against the end surface of the second end portion 12 c ofthe second type of nut 12. In this case, the notches 111 c may be cutout from the side instead of the tip end of the peripheral wall portion111 b. Further, the notches 111 c need only to connect thewrong-assembly detection gap 135 to the space into which molten resin isinjected from outside of the forming die 101. That is, a hole throughthe first mounting member 111 or a cutout formed along the peripheralwall portion 111 b on the wrong-assembly detection gap 135 side of theperipheral wall portion 111 b or the like may be used instead of thenotches 111 c.

Also, in the example embodiment described above, the insert moldedarticle may be a resin molded article other than a case for anelectronic control unit (ECU).

Also, in this example embodiment described above, the specific insertparts for which a plurality of types of parts are used may be parts(e.g., rod-shaped parts) other than insert nuts.

The invention may be applied to an insert molded article in which aplurality of types of parts are used for specific insert parts, aninsert molding method for manufacturing this insert molded article, andan insert molding apparatus used in this insert molding method, and thelike.

What is claimed is:
 1. A insert molding method for forming an insertmolded article that includes a first part, and a resin case that isformed exposing a portion of the first part, and having a protrudingportion that is adjacent to a portion where the first part is exposed,and protrudes from a surface of the resin case, the method comprising:arranging the first part in a forming die; arranging a mounting partthat has a passage that passes through a cross-section thereof, so as tocover a portion where the first part is exposed from the resin case andsuch that the passage is blocked off by the first part; and forming theresin case by pouring molten resin into the forming die.
 2. The insertmolding method according to claim 1, further comprising: arranging thesecond part in the forming die before forming the resin case.
 3. Theinsert molding method according to claim 2, wherein the first part is acylindrical insert nut; a portion where the first part is exposed fromthe resin case are top surface and a portion of a side surface of thefirst part; the second part is a cylindrical insert nut; a portion wherethe second part is exposed from the resin case are at least top surfaceof the second part; and a diameter of the top surface of the first partis smaller than a diameter of the top surface of the second part.